We previously reported that several stresses can induce cytokine-induced neutrophil chemoattractant expression in a nuclear factor B (NF-B)-dependent manner. In this study, we focused further on the regulation of NF-B. The activation of NF-B and the subsequent cytokine-induced neutrophil chemoattractant induction in response to interleukin-1␤ (IL-1␤) were inhibited by proteasome inhibitors, MG132 and proteasome inhibitor I. Translocation of NF-B into nuclei occurs by the phosphorylation, multi-ubiquitination, and degradation of IB␣, a regulatory protein of NF-B. Nascent IB␣ began to degrade 5 min after treatment with IL-1␤ and disappeared completely after 15 min. However, IB␣ returned to basal levels after 45-60 min. Interestingly, resynthesized IB␣ was already phosphorylated at Ser-32. These results suggest that 1) the upstream signals are still activated, although the translocation of NF-B peaks at 15 min; and 2) the regulated protein(s) acts downstream of IB␣ phosphorylation. Western blotting showed that the resynthesized and phosphorylated IB molecules were also upward-shifted by multi-ubiquitination in response to IL-1␤ treatment. On the other hand, ATP-dependent Leu-Leu-Val-Tyr cleaving activity transiently increased, peaked at 15 min, and then decreased to basal levels at 60 min. Furthermore, the cytosolic fraction that was stimulated by IL-1␤ for 15 min, but not for 0 and 60 min, could degrade phosphorylated and multi-ubiquitinated IB␣. These results indicate that the transient translocation of NF-B in response to IL-1␤ may be partly dependent on transient proteasome activation. Nuclear factor B (NF-B)1 participates in the regulation of the expression of multiple immediate-early genes involved in immune, acute-phase, and inflammatory responses (1). NF-B is a heterodimer protein of the Rel family of transcription factors. In mammalian cells, the factors include p65 (RelA), RelB, c-Rel, p50/p105 (NF-B1), and p52/p100 (NF-B2). NF-B proteins are constitutively present in cells and are retained in the cytoplasm associated with the inhibitory protein IB (2, 3). Activated NF-B complexes, typically composed of p50 and p65, are translocated to the nucleus in response to several cytokines (TNF-␣, IL-1␤, and IL-2), bacterial endotoxin, and stresses (UV, H 2 O 2 ).(1, 4 -6). The activation of NF-B appears to require the phosphorylation and degradation of the IB proteins, thereby allowing the rapid translocation of NF-B from the cytoplasm to the nucleus (4, 7-9). In particular, it has been shown that the phosphorylation of Ser-32 and Ser-36 and the ubiquitination at Lys-21 and Lys-22 are essential for targeting IB for signal-induced degradation by the ubiquitin/proteasome system (10). The ubiquitin-dependent degradation of regulatory shortlived proteins plays an important role in cellular processes, including the cell cycle, immune system functions, inflammatory responses, and tissue differentiation. A key element in the regulation process is E3, a member of the ubiquitin-substrate ligase family of enzymes. After bin...

Polyoxometalates (POMs) have been widely reported in recent years. These molecular metal oxides, or polyanions, are most commonly constructed of tungsten, molybdenum, or vanadium ions in their highest oxidation state, bridged by oxide ligands to form clusters which can range in size from low-nuclearity building blocks to large-scale protein-like superstructures.[1] An archetypical POM structural motif is the {XM 12 O 40 } nÀ species (X = P, Si…) known as the Keggin anion and Keggin structures have been successfully shown to act as catalysts [2] among other potential applications.[3] POMs are inorganic materials that can be functionalized through their combination with organic ligands and/or the introduction of paramagnetic heterometal ions which leads to magnetic heterometallic POMs. [4][5][6] In addition, there are a few studies of related species consisting exclusively of late first-row transition-metal ions such as some mixed-valence manganese Keggin-related clusters described by Lampropoulos et al, [7] the uncapped {Fe 13 } cluster reported by Bino et al., [8] and the reverse-Keggin structures presented by Baskar et al. [9] To the best of our knowledge, there are no other examples of POM-type complexes consisting exclusively of open-shell transition metals, and so far their physical properties have been barely investigated. In contrast, transition-metal oxide materials are widely used and their properties such as magnetic ordering, semi-and superconductivity, giant magnetoresistance, and ferroelectricity are much studied. Their electronic properties can be understood by their band structures and changed to show the desired characteristics. [10,11] Replication or improvement of metal oxide properties in discrete molecules can be extremely difficult. However, molecular metal clusters can possess wellseparated energy levels and their characteristic electronic structures can be altered to show, for example, valence tautomerism, multi-bistability with spin crossover, and singlemolecule-magnetic (SMM) behavior by tuning the frontier orbitals and the electronic interactions between the metal centers. [12][13][14][15] The band filling in solids is readily controlled in their syntheses by altering the ratio of the constituent elements which drastically changes the physical properties. The question arises whether the chemist can synthesize metal oxide clusters displaying controllable redox states which can perturb the physical properties.Herein, a polyoxometalate-type cluster was synthesized by using exclusively first-row transition-metal ions in combination with organic capping ligands. In the resultant system the spin state and magnetic properties were tuned without substantial change to the molecular structure, and its SMM behavior was perturbed through manipulation of the cluster oxidation state. Herein, the synthesis, magnetic properties, and redox behavior of three mixed-valence {Mn 13 } Keggintype clusters are reported.The one-pot reaction of Mn(NO 3 ) 2 ·6 H 2 O with 2,6-bis[N-(2-hydroxyethyl)iminomethyl]-4-met...

Four cDNA clones (SlArf/Xyl1-4) encoding α-l-arabinofuranosidase/β-xylosidase belonging to glycoside hydrolase family 3 were obtained from tomato (Solanum lycopersicum) fruit. SlArf/Xyl1 was expressed in various organs. Its level was particularly high in flower and leaves but low in fruit. SlArf/Xyl3 was highly expressed in flower. On the contrary, SlArf/Xyl2 and 4 were expressed in early developmental stage in various organs. Comparison with SlArf/Xyl4, SlArf/Xyl2 expression was observed in earlier stages. The active recombinant proteins were obtained by using BY-2 tobacco (Nicotiana tabacum) suspension cultured cells. The SlArf/Xyl1 and 2 recombinant proteins showed a bi-functional activity of α-l-arabinofuranosidase/β-xylosidase while the SlArf/Xyl4 protein possessed a β-xylosidase activity predominantly. Neither enzyme activities were detected for the SlArf/Xyl3 protein under the same conditions. Although SlArf/Xyl2 possessed a bi-functional activity, it preferentially hydrolyzed arabinosyl residues from tomato hemicellulosic polysaccharides. Antisense suppression of SlArf/Xyl2 resulted in no apparent changes in the enzyme activities, monosaccharide composition or fruit phenotype. Increment of a family 51 α-l-arabinofuranosidase expression rather than that of family 3 resulted in a restoring the activity in SlArf/Xyl2-suppressed fruit. The ability of recombinant SlArf/Xyl2 to hydrolyze both arabinan and arabinoxylan is nearly identical to that of α-l-arabinofuranosidases belonging to family 51. Our results suggested that BY-2 cells are a useful expression system for obtaining active cell wall hydrolyzing enzymes. In addition, an α-l-arabinofuranosidase activity derived from SlArf/Xyl2 would be essential in young organ development and the action of the enzyme could be restored by the other enzyme belonging to a different family under a defective condition.

Densely packed redox-active self-assembled monolayers (SAMs) of monocarbonyl triruthenium complexes [Ru3(μ3-O)(μ-CH3COO)6(CO)(mpy)(C10PY)] (1) (mpy, 4-methylpyridine; C10PY, {(NC5H4)CH2NHC(O)(CH2)10S–}2), [Ru3(μ3-O)(μ-CH3COO)6(CO)(μ-C10PY)] (2), and [{Ru3(μ3-O)(μ-CH3COO)6(CO)(mpy)}2(μ-C10PY)] (3) have been constructed on an Au(111) electrode surface. They were characterized by infrared reflection absorption spectroscopy (IRRAS), spectroscopic ellipsometry, and contact angle measurement as well as cyclic voltammetry. Redox potential of the SAMs of 1 at the interface of aqueous electrolyte solutions shifted negatively as the concentration of HClO4 increased from 0.01 to 1.0 mol dm−3 with the slope of 0.059 V/decade and as the electrolyte was changed from H2SO4 (0.79 V vs. Ag|AgCl) to HNO3 (0.69 V) and HClO4 (0.59 V) at a fixed concentration of 0.1 mol dm−3. No significant difference in the redox potential was observed between the acid and its sodium salt. The effect is explained, as previously reported for the ferrocenylalkanethiol and non-carbonyl triruthenium SAMs, in terms of the effective ion pair formation in the order ClO4− > NO3− > SO42−. The rate of the CO dissociation reaction of the complex in the SAMs (complete within a few minutes at room temperature) that occurs in the oxidation state of Ru3III,III,III was not very sensitive to the applied electrode potential (0.6–0.8 V), but increased by ca. 2.5 times as the concentration of HClO4 (0.01–1.0 mol dm−3) was lowered, and by ca. one-order of magnitude as the electrolyte anions was changed from ClO4− to SO42− and NO3−.

Stärkeres magnetisches Moment mit weniger Elektronen: Der α‐Keggin‐Einzelmolekülmagnet {Mn13} wurde hergestellt und oxidiert (siehe Bild); die Ein‐ und Zwei‐Elektronen‐Oxidationsprodukte konnten isoliert werden. Die Spingrundzustände der stärker oxidierten Verbindungen liegen trotz des Elektronenverlustes höher, was zur Verstärkung der magnetischen Eigenschaften führt.